Checked out Klout service. The idea is portray how influential one is within their network and to portray how others influence you. The data is collected through social networks and give a "score" based on the findings.
The service also identifies 5 topics one is "influential on." I consider myself well-read in some aspects of technology as well as religion and spirituality. However, I have never been to Reno nor Yale. I do not know much about teeth and orthodontology (aside from avoiding the dentist lately).
I don't have much faith in klout's ability to determine if I am influential or authoritative on a topic. It's an interesting concept, but in reality, our sphere of influence is much greater than twitter and other social network mediums.